This invention relates to the field of network analysis, and in particular to a method and system that facilitates the updating of virtual devices, such as switches and routers, in a network that is modeled for a network simulator or other network analysis tool.
Network managers often use models of their network to assess proposed changes to the network, or to contrast the performance of the actual network to the ‘idealized’ performance of the modeled network.
FIG. 1 illustrates an example conventional network analysis system, wherein a network of devices is modeled for execution on a variety of simulation tools 190. A plurality of devices form the nodes of the network, and the configuration of these devices define how these devices are configured to communicate with each other. The device configuration data 110 will generally include the parameters related to the communication of data to and from each device, including, for example, the address of the node, the protocols used, and the parameters and options associated with the protocols, such as routing and switching parameters, failure recovery and security options, system management details, and so on. If the device includes multiple communication modes or channels, the configuration data 110 includes sets of parameters for each mode or channel.
A configuration compiler 130 transforms the configuration data in the configuration database 110 into a processable form 140 that represents each device in the network. A network inference engine 150 processes the device representations to infer the topology of the network and to create a network model 160 that is suitable for simulation 190.
The simulator 190 is commonly used to perform ‘what-if’ analyses, wherein a proposed change to the network is modeled via one or more changes to the device configuration 110. If the modeled change exhibits the expected change (e.g. a performance increase or enhanced security), the actual network of devices is correspondingly updated to conform to the modeled network, and the changed configuration 110 is stored as the new ‘baseline’ configuration for the current network. If the simulation demonstrates unexpected performance, on the other hand, the proposed changes are removed from the configuration database 110, typically by restoring the configuration parameters in the database 110 to their prior state. In many instances, however, because changes to an operational network are generally an ongoing sequence of changes, a restoration of the model to a prior configuration may required going beyond the immediately prior model to effect the restoration. Although sets of backup copies of the device configuration database may be maintained, it is often difficult to identify the particular changes associated with each backup. Generally, processes and policies put in place to manage such changes, by requiring each person to document each change, for example, but often these processes and policies are not strictly adhered to.
Additionally, device configuration database 110 for most non-trivial networks are quite large, and complex. The task of adding a change to the database 110 can be daunting, and the time required to recompile the configuration database 110 can be substantial. In such cases, changes are often effected in the actual network without first modeling the proposed change. Often, for example, a local support engineer may propose and/or implement an upgrade to the configuration of equipment at a node, such as “reconfigure router ‘abc’ to restrict traffic per access table A”. In many instances, the overhead associated with finding and editing the appropriate entry in database 110 to effect this modeled reconfiguration, and performing a successful recompilation is substantially greater than the time and effort required to actually reconfigure the component in the actual network, and the local update is not incorporated into the configuration database 110.
It is an objective of this invention to provide a method and system that eases the task of configuration management of complex networks. It is a further objective of this invention to provide a method and system that facilitates ‘what-if’ analyses of configuration changes in complex networks without substantial overhead.
These objectives, and others, are achieved by a method and system that facilitates incremental updates to configuration data of modeled networks. Each incremental change is identified and logged, to facilitate configuration management and to facilitate select roll-backs to prior configurations. Because each update is processed and managed individually, and integrated automatically into the overall system configuration, the overhead associated with keeping a configuration database up-to-date is substantially reduced, thereby increasing the likelihood that all configuration changes will be reflected in the modeled network. In a preferred embodiment, the same data is used to incrementally update the configuration model and to execute the change in the actual system, thereby further reducing the overhead and assuring a correspondence between the modeled network and the actual network.
Throughout the drawings, the same reference numerals indicate similar or corresponding features or functions. The drawings are included for illustrative purposes and are not intended to limit the scope of the invention.